A swash plate type variable capacity compressor used in an air-conditioning system of an automobile or the like includes a rotating shaft rotatably driven by a rotational force of an engine, a swash plate coupled to the rotating shaft so that the angle of inclination can be varied, a piston for compression coupled to the swash plate, and the like, and varies a stroke of the piston by varying the angle of inclination of the swash plate and controls the discharge rate of a refrigerant gas.
The angle of inclination of the swash plate can be continuously varied by adjusting the state of balance of the pressure acting on both faces of the piston through appropriate control of a pressure in a control chamber (crank chamber) using a capacity control valve driven to be opened and closed by an electromagnetic force while using a suction chamber pressure of a suction chamber suctioning a refrigerant gas, a discharge chamber pressure of a discharge chamber discharging the refrigerant gas pressurized by the piston, and a control chamber pressure of the control chamber accommodating the swash plate.
As this type of capacity control valve, as shown in FIG. 9, such a valve is known that includes a body 70 formed of a metal material or a resin material, discharge-side passages 73, 77 formed in the body 70 and providing communication between a discharge chamber and a control chamber, a first valve chamber formed in the middle of the discharge-side passages, suction-side passages 71, 72, 74 providing communication between a suction chamber and the control chamber, a second valve chamber (operation chamber) 83 formed in the middle of the suction-side passages, a valving element 81 formed so that a first valve portion 76 disposed in the first valve chamber 82 and opening and closing the discharge-side passages 73, 77 and a second valve portion 75 disposed in the second valve chamber 83 and opening and closing the suction-side passages 71, 72, 74 are integrally reciprocated and at the same time, perform opening and closing operation in the opposite direction to each other, a third valve chamber 84 formed nearer to the control chamber in the middle of the suction-side passages 71, 72, 74, a pressure sensitive body (bellows) 78 disposed in the third valve chamber and exerting an urging force in a direction of extension (expansion), and contracting in accordance with pressure increase of the surroundings, a valve seat body 80 provided on a free end in the extension and contraction direction of the pressure sensitive body and having an annular seat face, a third valve portion 79 capable of moving integrally with the valving element 81 in the third valve chamber 84, and opening and closing the suction-side passages by engagement and disengagement of the valve seat body 80, a solenoid S connected to the body 70 and exerting an electromagnetic driving force on the valving element 81, and the like (Hereinafter, referred to as a “conventional art”. For example, see Patent Citations 1 and 2).
Then, in this capacity control valve V, even though a clutch mechanism is not provided in the variable capacity compressor at capacity control, the pressure in the control chamber (control chamber pressure) Pc can be adjusted by providing communication between the discharge chamber and the control chamber if the control chamber pressure needs to be changed. In addition, if the control chamber pressure Pc rises in the stop state of the variable capacity compressor, the third valve portion (valve opening joint portion) 79 is disengaged from the valve seat body (engagement portion) 80 and opens the suction-side passages, thereby providing communication between the suction chamber and the control chamber.
By the way, if the swash plate type variable capacity compressor is stopped and caused to be started after being left for a long time, the liquid refrigerant (the cooled and liquefied refrigerant gas during leaving) accumulates in the control chamber (crank chamber), so that the discharge rate as setting cannot be secured by compressing the refrigerant gas unless discharging the liquid refrigerant.
To perform a desired capacity control from immediately after the start-up, the liquid refrigerant in the control chamber (crank chamber) needs to be discharged as rapidly as possible.
In the capacity control valve 70 of the conventional art, if the variable capacity compressor is left in the stop state for a long time in a state that the solenoid S is firstly turned off and the second valve portion 75 closes the suction-side passages 71, 72, 74, the liquid refrigerant accumulates in the control chamber (crank chamber) of the variable capacity compressor. If the stopping time of the variable capacity compressor is long, the internal pressure of the variable capacity compressor becomes uniform, and the control chamber pressure Pc is much higher than the control chamber pressure Pc and the suction chamber pressure Ps when driving the variable capacity compressor.
In this state, when the solenoid S is turned on and the valving element 81 begins to start, the first valve portion 76 is moved to the valve-opening direction and at the same time, the second valve portion 75 is moved to the valve-opening direction, and then the second valve portion 75 is opened. At that time, when the control chamber pressure Pc contracts the pressure sensitive body 78, the third valve portion 79 is disengaged from the valve seat body 80 and the third valve portion 79 is opened, and then the liquid refrigerant in the control chamber is discharged from the suction-side passages 71, 72, 74 into the suction chamber of the variable capacity compressor. Then, when the control chamber pressure Pc drops below a predetermined level, the pressure sensitive body 78 elastically returns and extends, and the third valve portion 79 is engaged with the valve seat body 80 and closed so as to close the suction-side passages 71, 72, 74.
In addition, the solenoid S of the conventional art includes a solenoid body 61 coupled to the body 70, a casing 62 surrounding the entirety, a sleeve 63 whose one end is closed, a cylindrical center post (fixed iron core) 64 disposed inside the solenoid body 61 and the sleeve 63, a driving rod 65 capable of reciprocating inside the center post 64 and having its tip end coupled to the valving element 81 so as to form the suction-side passages 71, 72, 74, a plunger (movable iron core) 66 fixed to the other end of the driving rod 65, a coil spring 67 for urging the plunger 66 in a direction to open the first valve portion 76, a coil 68 for excitation wound outside the sleeve 63 through a bobbin, and the like.
In the above configuration, when the coil 68 is not energized, the valving element 81 is moved to the upper side in FIG. 9 by the urging force of the pressure sensitive body 78 and the coil spring 67, the first valve portion 76 is separated from the seat face 77 to open the discharge-side passages 73, 77 and at the same time, the second valve portion 75 is seated on a seat face 83a to close the suction-side passages 71, 72, 74. At this time, when the control chamber pressure Pc rises above the predetermined level, the pressure sensitive body 78 is contracted to retreat and disengage the valve seat body 80 from the third valve portion 79.
On the other hand, when the coil 68 is energized to a predetermined current value (I) or more, by the electromagnetic driving force (urging force) of the solenoid S acting in a direction opposite to the urging force of the pressure sensitive body 78 and the coil spring 67, the valving element 81 is moved to the lower side in FIG. 9, the first valve portion 76 is seated on the seat face 77 to close the discharge-side passages 73, 77 and at the same time, the second valve portion 75 is separated from the seat face 83a to open the portion of the second valve portion 75 in the suction-side passages 71, 72, 74. Immediately after this start-up, when the control chamber pressure Pc is above the predetermined level, the valve seat body 80 is disengaged from the third valve portion 79 to open the suction-side passages 71, 72, 74. For the period from this state till when the third valve portion 79 is seated on the valve seat body 80, the liquid refrigerant or the like accumulating in the control chamber 12 is discharged into the suction chamber 13 via the suction-side passages 71, 72, 74.
However, in the conventional art, since the center post (fixed iron core) 64 is fixed to the solenoid body 61, a second liquid refrigerant discharge valve is limited at a maximum to a passage area formed between the second liquid refrigerant discharge valve, which is at the maximum lowered position of the second liquid refrigerant discharge valve determined by the stroke of the plunger 66, and the seat face 83a, so that there was a limit on the discharge rate of the liquid refrigerant per unit time.